In recent years, display devices have been popularly used which are thin, lightweight, and low in electric power consumption, and are typified by liquid crystal display devices. Such a display device is suitably provided to, for example, a device such as a mobile phone, a smartphone, or a tablet terminal so that the device is smaller in size and lighter in weight. Such a device, in which a storage battery is used as a voltage source, is required to consume less electric power. Accordingly, the display device to be provided to the device is also required to consume less electric power.
In order to maintain a stable display state, the display device carries out refresh driving such that an identical image is repeatedly displayed at regular intervals (i.e., an image is rewritten). However, since electric power is consumed in the refresh driving, an attempt has been made to reduce the electric power consumption.
For example, Patent Literature 1 discloses a driving method in which after a screen is scanned, a pause period is provided (i) which is a non-scanning period longer than a scanning period in which the screen is scanned one time and (ii) in which all scanning signal lines are in a non-scanning state. In a case where such a pause period is provided, it is possible to reduce electric power consumption.
Moreover, according to the driving method, it is detected whether or not image data changes, and the pause period is provided so as to vary in accordance with an unchanging image (still image) or a changing image (moving image). Specifically, in the case of the still image (a still image mode), a scanning period (one frame) and the pause period are alternately repeated, whereas in the case of the moving image (a moving image mode), a plurality of scanning periods and one pause period are repeated. According to this, especially in a case where the moving image is displayed, it is possible to ensure a sufficient response speed at the display, and to easily and sufficiently reduce electric power consumption while basic display qualities such as a brightness, a contrast, a response speed, and a graduation characteristic are satisfied. Furthermore, while optimum display qualities of the still image and the moving image are satisfied, electric power consumption can be reduced by causing an image to be rewritten fewer times.